Abstract
The theory of stellar structure and evolution plays a pivotal role in modern astrophysics. Stellar evolution calculations are used to determine the ages and, to a lesser extent, distances of stars, which are critical to our knowledge of the history and structure of galaxies. Moreover, since virtually all chemical elements (except hydrogen) can be synthesized inside stars, knowing the chemical history of the Universe requires understanding stellar evolution. Here, we briefly outline the basic physical processes at work in stellar structures and examine some of the most relevant aspects of the life of stars.